1
|
Pharmacological properties and biochemical mechanisms of μ-opioid receptor ligands might be due to different binding poses: MD studies. Future Med Chem 2020; 12:2001-2018. [PMID: 32972243 DOI: 10.4155/fmc-2020-0249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Background: Central and peripheral analgesia without adverse effects relies on the identification of μ-opioid agonists that are able to activate 'basal' antinociceptive pathways. Recently developed μ-selective benzomorphan agonists that are not antagonized by naloxone do not activate G-proteins and β-arrestins. Which pathways do μ receptors activate? How can each of them be selectively activated? What role is played by allosteric binding sites? Methodology & results: Molecular modeling studies characterize the amino acid residues involved in the interaction with various classes of endogenous and exogenous ligands and with agonists and antagonists. Conclusions: Critical binding differences between various classes of agonists with different pharmacological profiles have been identified. MML series binding poses may be relevant in the search for an antinociception agent without side effects.
Collapse
|
2
|
Nakamura T, Ramos-Álvarez I, Iordanskaia T, Moreno P, Mantey SA, Jensen RT. Molecular basis for high affinity and selectivity of peptide antagonist, Bantag-1, for the orphan BB3 receptor. Biochem Pharmacol 2016; 115:64-76. [PMID: 27346274 DOI: 10.1016/j.bcp.2016.06.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 06/21/2016] [Indexed: 12/15/2022]
Abstract
Bombesin-receptor-subtype-3 (BB3 receptor) is a G-protein-coupled-orphan-receptor classified in the mammalian Bombesin-family because of high homology to gastrin-releasing peptide (BB2 receptor)/neuromedin-B receptors (BB1 receptor). There is increased interest in BB3 receptor because studies primarily from knockout-mice suggest it plays roles in energy/glucose metabolism, insulin-secretion, as well as motility and tumor-growth. Investigations into its roles in physiological/pathophysiological processes are limited because of lack of selective ligands. Recently, a selective, peptide-antagonist, Bantag-1, was described. However, because BB3 receptor has low-affinity for all natural, Bn-related peptides, little is known of the molecular basis of its high-affinity/selectivity. This was systematically investigated in this study for Bantag-1 using a chimeric-approach making both Bantag-1 loss-/gain-of-affinity-chimeras, by exchanging extracellular (EC) domains of BB3/BB2 receptor, and using site-directed-mutagenesis. Receptors were transiently expressed and affinities determined by binding studies. Bantag-1 had >5000-fold selectivity for BB3 receptor over BB2/BB1 receptors and substitution of the first EC-domain (EC1) in loss-/gain-of affinity-chimeras greatly affected affinity. Mutagenesis of each amino acid difference in EC1 between BB3 receptor/BB2 receptor showed replacement of His(107) in BB3 receptor by Lys(107) (H107K-BB3 receptor-mutant) from BB2 receptor, decreased affinity 60-fold, and three replacements [H107K, E11D, G112R] decreased affinity 500-fold. Mutagenesis in EC1's surrounding transmembrane-regions (TMs) demonstrated TM2 differences were not important, but R127Q in TM3 alone decreased affinity 400-fold. Additional mutants in EC1/TM3 explored the molecular basis for these changes demonstrated in EC1, particularly important is the presence of aromatic-interactions by His(107), rather than hydrogen-bonding or charge-charge interactions, for determining Bantag-1 high affinity/selectivity. In regard to Arg(127) in TM3, both hydrogen-bonding and charge-charge interactions contribute to the high-affinity/selectivity for Bantag-1.
Collapse
Affiliation(s)
- Taichi Nakamura
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-1804, USA
| | - Irene Ramos-Álvarez
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-1804, USA
| | - Tatiana Iordanskaia
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-1804, USA
| | - Paola Moreno
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-1804, USA
| | - Samuel A Mantey
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-1804, USA
| | - R T Jensen
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-1804, USA.
| |
Collapse
|
3
|
Váradi A, Palmer TC, Haselton N, Afonin D, Subrath JJ, Le Rouzic V, Hunkele A, Pasternak GW, Marrone GF, Borics A, Majumdar S. Synthesis of Carfentanil Amide Opioids Using the Ugi Multicomponent Reaction. ACS Chem Neurosci 2015; 6:1570-7. [PMID: 26148793 DOI: 10.1021/acschemneuro.5b00137] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
We report a novel approach to synthesize carfentanil amide analogues utilizing the isocyanide-based four-component Ugi multicomponent reaction. A small library of bis-amide analogues of carfentanil was created using N-alkylpiperidones, aniline, propionic acid, and various aliphatic isocyanides. Our lead compound showed high affinity for mu (MOR) and delta opioid receptors (DOR) with no appreciable affinity for kappa (KOR) receptors in radioligand binding assays. The compound was found to be a mixed MOR agonist/partial DOR agonist in [(35)S]GTPγS functional assays, and it showed moderate analgesic potency in vivo. The compound showed no visible signs of physical dependence or constipation in mice. In addition, it produced less respiratory depression than morphine. Most mixed MOR/DOR opioids reported in the literature are peptides and thereby systemically inactive. Our approach utilizing a multicomponent reaction has the promise to deliver potent and efficacious small-molecule analgesics with potential clinical utility.
Collapse
Affiliation(s)
- András Váradi
- Department
of Neurology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Travis C. Palmer
- Department
of Neurology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Nathan Haselton
- Department
of Neurology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Daniel Afonin
- Department
of Neurology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Joan J. Subrath
- Department
of Neurology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Valerie Le Rouzic
- Department
of Neurology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Amanda Hunkele
- Department
of Neurology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Gavril W. Pasternak
- Department
of Neurology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Gina F. Marrone
- Department
of Neurology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Attila Borics
- Institute
of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, Szeged, Hungary H-6726
| | - Susruta Majumdar
- Department
of Neurology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| |
Collapse
|
4
|
Abstract
Opiates are among the oldest medications available to manage a number of medical problems. Although pain is the current focus, early use initially focused upon the treatment of dysentery. Opium contains high concentrations of both morphine and codeine, along with thebaine, which is used in the synthesis of a number of semisynthetic opioid analgesics. Thus, it is not surprising that new agents were initially based upon the morphine scaffold. The concept of multiple opioid receptors was first suggested almost 50 years ago (Martin, 1967), opening the possibility of new classes of drugs, but the morphine-like agents have remained the mainstay in the medical management of pain. Termed mu, our understanding of these morphine-like agents and their receptors has undergone an evolution in thinking over the past 35 years. Early pharmacological studies identified three major classes of receptors, helped by the discovery of endogenous opioid peptides and receptor subtypes-primarily through the synthesis of novel agents. These chemical biologic approaches were then eclipsed by the molecular biology revolution, which now reveals a complexity of the morphine-like agents and their receptors that had not been previously appreciated.
Collapse
Affiliation(s)
- Gavril W Pasternak
- Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, NY 10065.
| | | |
Collapse
|
5
|
Interaction and regulatory functions of μ- and δ-opioid receptors in nociceptive afferent neurons. Neurosci Bull 2012; 28:121-30. [PMID: 22466123 DOI: 10.1007/s12264-012-1206-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
μ-opioid receptor (MOR) agonists such as morphine are powerful analgesics used for pain therapy. However, the use of these drugs is limited by their side-effects, which include antinociceptive tolerance and dependence. Earlier studies reported that MOR analgesic tolerance is reduced by blockade of δ-opioid receptors (DORs) that interact with MORs. Recent studies show that the MOR/DOR interaction in nociceptive afferent neurons in the dorsal root ganglion may contribute to morphine analgesic tolerance. Further analysis of the mechanisms for regulating the trafficking of receptors, ion channels and signaling molecules in nociceptive afferent neurons would help to understand the nociceptive mechanisms and improve pain therapy.
Collapse
|
6
|
|
7
|
Sacharczuk M, Lesniak A, Korostynski M, Przewlocki R, Lipkowski A, Jaszczak K, Sadowski B. A polymorphism in exon 2 of the δ-opioid receptor affects nociception in response to specific agonists and antagonists in mice selectively bred for high and low analgesia. Pain 2010; 149:506-513. [DOI: 10.1016/j.pain.2010.03.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Revised: 02/23/2010] [Accepted: 03/15/2010] [Indexed: 01/21/2023]
|
8
|
|
9
|
Khurshid N, Hameed LS, Mohanasundaram S, Iyengar S. Opioid modulation of cell proliferation in the ventricular zone of adult zebra finches (Taenopygia guttata). FASEB J 2010; 24:3681-95. [PMID: 20495180 DOI: 10.1096/fj.09-146746] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Besides modulating pain, stress, physiological functions, motivation, and reward, the opioid system has been implicated in developmental and adult mammalian neurogenesis and gliogenesis. In adult male songbirds including zebra finches, neurons generated from the ventricular zone (VZ) of the lateral ventricles are incorporated throughout the telencephalon, including the song control nuclei, HVC, and area X. Although the endogenous opioid met-enkephalin is present in neurons adjacent to the VZ and is upregulated in song control regions during singing, it is not known whether the opioid system can modulate adult neurogenesis/gliogenesis in zebra finches. We used quantitative RT-PCR and in situ hybridization to demonstrate that μ- and δ-opioid receptors are expressed by the VZ of adult male zebra finches. Treating cultured VZ cells from male birds with the opioid antagonist naloxone led to an increase in cell proliferation measured by 5-bromo-2-deoxyuridine incorporation, whereas administering met-enkephalin had the opposite effect, compared with saline-treated cultures. Systemically administering naloxone (2.5 mg/kg body wt) to adult male zebra finches for 4 d also led to a significant increase in cell proliferation in the ventral VZ of these birds, compared with saline-treated controls. Our results show that cell proliferation is augmented by naloxone in the VZ adjacent to the anterior commissure, suggesting that the endogenous opioids modulate adult neurogenesis/gliogenesis by inhibiting cell proliferation in songbirds.
Collapse
Affiliation(s)
- Nazia Khurshid
- Division of Systems Neuroscience, National Brain Research Centre, Manesar, India
| | | | | | | |
Collapse
|
10
|
Structural comparison of μ-opioid receptor selective peptides confirmed four parameters of bioactivity. J Mol Graph Model 2010; 28:495-505. [DOI: 10.1016/j.jmgm.2009.11.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Revised: 11/24/2009] [Accepted: 11/27/2009] [Indexed: 11/18/2022]
|
11
|
Brasel CM, Sawyer GW, Stevens CW. A pharmacological comparison of the cloned frog and human mu opioid receptors reveals differences in opioid affinity and function. Eur J Pharmacol 2008; 599:36-43. [PMID: 18930720 DOI: 10.1016/j.ejphar.2008.09.043] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Revised: 09/23/2008] [Accepted: 09/29/2008] [Indexed: 10/21/2022]
Abstract
This study presents a direct comparison of the ligand binding and signaling profiles of a mammalian and non-mammalian mu opioid receptor. Opioid ligand binding and agonist potencies were determined for an amphibian (Rana pipiens) mu opioid receptor (rpMOR) and the human mu opioid receptor (hMOR) in transfected, intact Chinese hamster ovary (CHO) cells. Identical conditions were employed such that statistically meaningful differences between the two receptors could be determined. Identifying these differences is an important first step in understanding how evolutionary changes affect ligand binding and signaling in vertebrate opioid receptors. As expected, the rank of opioid ligand affinity for rpMOR and hMOR was consistent with the ligands' previously characterized type-selectivity. However, most of the opioid ligands tested had significant differences in affinity for rpMOR and hMOR. For example, the mu-selective agonist, DAMGO ([d-Ala(2), N-Me-Phe(4), Gly(5)-ol]-enkephalin), had a 10.9-fold greater affinity (K(i)) for hMOR (K(i)=268 nM) than rpMOR (K(i)=2914 nM). In addition, differences in signaling between these receptors were found by measuring inhibition of cAMP accumulation by morphine or DAMGO. DAMGO was significantly more potent (13.6-fold) in CHO cells expressing hMOR versus those expressing rpMOR. In addition, a significantly greater maximal inhibition was elicited by both opioid agonists in cells expressing hMOR. In summary, this study supports an ongoing effort to better understand how vertebrate evolution has shaped opioid receptor properties and function.
Collapse
Affiliation(s)
- Chris M Brasel
- Dept. of Pharmacology and Physiology, OSU-Center for Health Sciences, Tulsa, OK 74107-1898, USA
| | | | | |
Collapse
|
12
|
Gonzalez N, Hocart SJ, Portal-Nuñez S, Mantey SA, Nakagawa T, Zudaire E, Coy DH, Jensen RT. Molecular basis for agonist selectivity and activation of the orphan bombesin receptor subtype 3 receptor. J Pharmacol Exp Ther 2007; 324:463-74. [PMID: 18006692 DOI: 10.1124/jpet.107.132332] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Bombesin receptor subtype (BRS)-3, a G-protein-coupled orphan receptor, shares 51% identity with the mammalian bombesin (Bn) receptor for gastrin-releasing peptide. There is increasing interest in BRS-3 because it is important in energy metabolism, glucose control, motility, and tumor growth. BRS-3 has low affinity for all Bn-related peptides; however, recently synthetic high-affinity agonists, [d-Tyr(6)/d-Phe(6),betaAla(11),Phe(13),Nle(14)]Bn-(6-14), were described, but they are nonselective for BRS-3 over other Bn receptors. Based on these peptides, three BRS-3-selective ligands were developed: peptide 2, [d-Tyr(6)(R)-3-amino-propionic acid(11),Phe(13),Nle(14)]Bn(6-14); peptide 3, [d-Tyr(6),(R)-Apa(11),4Cl-Phe(13),Nle(14)]Bn(6-14); and peptide 4, acetyl-Phe-Trp-Ala-His-(tBzl)-piperidine-3 carboxylic acid-Gly-Arg-NH(2). Their molecular determinants of selectivity/high affinity for BRS-3 are unknown. To address this, we used a chimeric/site mutagenesis approach. Substitution of extracellular domain 2 (EC2) of BRS-3 by the comparable gastrin-releasing peptide receptor (GRPR) domain decreased 26-, 4-, and 0-fold affinity for peptides 4, 3, and 2. Substitution of EC3 decreased affinity 4-, 11-, and 0-fold affinity for peptides 2 to 4. Ten-point mutations in the EC2 and adjacent transmembrane regions (TM2) 2 and 3 of BRS-3 were made. His107 (EC2-BRS-3) for lysine (H107K) (EC2-GRPR) decreased affinity (25- and 0-fold) for peptides 4 and 1; however, it could not be activated by either peptide. Its combination with Val101 (TM2), Gly112 (EC2), and Arg127 (TM3) resulted in complete loss-of-affinity of peptide 4. Receptor-modeling showed that each of these residues face inward and are within 4 A of the binding pocket. These results demonstrate that Val101, His107, Gly112, and Arg127 in the EC2/adjacent upper TMs of BRS-3 are critical for the high BRS3 selectivity of peptide 4. His107 in EC2 is essential for BRS-3 activation, suggesting amino-aromatic ligand/receptor interactions with peptide 4 are critical for both binding and activation. Furthermore, these result demonstrate that even though these three BRS-3-selective agonists were developed from the same template peptide, [d-Phe(6),betaAla(11),Phe(13),Nle(14)]Bn-(6-14), their molecular determinants of selectivity/high affinity varied considerably.
Collapse
Affiliation(s)
- Nieves Gonzalez
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Heath, Building 10, Room 9C-103, 10 Center Dr. MSC 1804, Bethesda, MD 20892-1804, USA
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Alvarez FA, Rodriguez-Martin I, Gonzalez-Nuñez V, Marrón Fernández de Velasco E, Gonzalez Sarmiento R, Rodríguez RE. New kappa opioid receptor from zebrafish Danio rerio. Neurosci Lett 2006; 405:94-9. [PMID: 16842913 DOI: 10.1016/j.neulet.2006.06.028] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2006] [Revised: 05/05/2006] [Accepted: 06/13/2006] [Indexed: 11/19/2022]
Abstract
A cDNA that encodes a kappa opioid receptor like from zebrafish (ZFOR3) has been cloned and characterized. The encoded protein is 377 residues long and presents 70% identity with the mammalian kappa receptors, although less homology is found in the amino- and carboxyl-terminus as well as in the extracellular loops. In situ hybridization studies have revealed that ZFOR3 mRNA is highly expressed in particular brain areas that coincide with the expression of the kappa opioid receptor in other species. When ZFOR3 is stably expressed in HEK293 cells, [(3)H]-diprenorphine binds with high affinity (K(D)=1.05+/-0.26 nM), being this value on the same range as those reported for mammalian kappa opioid receptors. On the other hand, the selective agonist for mammalian kappa receptors U69,593 does not bind to ZFOR3. [(3)H]-diprenorphine binding is readily displaced by the peptidic ligand dynorphin A and by the non-endogenous compounds bremazocine, naloxone and morphine, although with different affinities. Our results demonstrate that ZFOR3 is a unique model to study the kappa opioid receptor functionality.
Collapse
Affiliation(s)
- Franscisco Alvar Alvarez
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Instituto de Neurociencias de Castilla y Leon, University of Salamanca, Avda. Alfonso X El Sabio s/n, 37007 Salamanca, Spain
| | | | | | | | | | | |
Collapse
|
14
|
Bradford CS, Walthers EA, Stanley DJ, Baugh MM, Moore FL. Delta and mu opioid receptors from the brain of a urodele amphibian, the rough-skinned newt Taricha granulosa: cloning, heterologous expression, and pharmacological characterization. Gen Comp Endocrinol 2006; 146:275-90. [PMID: 16375901 DOI: 10.1016/j.ygcen.2005.11.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2005] [Revised: 10/31/2005] [Accepted: 11/03/2005] [Indexed: 11/20/2022]
Abstract
Two full-length cDNAs, encoding delta (delta) and mu (mu) opioid receptors, were cloned from the brain of the rough-skinned newt Taricha granulosa, complementing previous work from our laboratory describing the cloning of newt brain kappa (kappa) and ORL1 opioid receptors. The newt delta receptor shares 82% amino acid sequence identity with a frog delta receptor and lower (68-70%) identity with orthologous receptors cloned from mammals and zebrafish. The newt mu receptor shares 79% sequence identity with a frog mu receptor, 72% identity with mammalian mu receptors, and 66-69% identity with mu receptors cloned from teleost fishes. Membranes isolated from COS-7 cells transiently expressing the newt delta receptor possessed a single, high-affinity (Kd = 2.4 nM) binding site for the nonselective opioid antagonist [3H]naloxone. In competition binding assays, the newt delta receptor displayed highest affinity for Met-enkephalin, relatively low affinity for Leu-enkephalin, beta-endorphin, and [D-penicillamine, D-penicillamine] enkephalin (DPDPE) (a delta-selective agonist in mammals), and very low affinity for mu-, kappa-, or ORL1-selective agonists. COS-7 cells expressing the newt mu receptor also possessed a high-affinity (Kd = 0.44 nM) naloxone-binding site that showed highest affinity for beta-endorphin, moderate-to-low affinity for Met-enkephalin and Leu-enkephalin and DAMGO (a mu-selective agonist in mammals), and very low affinity for DPDPE and kappa- or ORL1-selective agonists. COS-7 cells expressing either receptor type (delta or mu) showed very high affinity (Kd = 0.1-0.3 nM) for the nonselective opioid antagonist diprenorphine. Taricha granulosa expresses the same four subtypes (delta, mu, kappa, and ORL1) of opioid receptors found in other vertebrate classes, but ligand selectivity appears less stringent in the newt than has been documented in mammals.
Collapse
MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- Brain Chemistry
- COS Cells
- Chlorocebus aethiops
- Cloning, Molecular
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/metabolism
- Enkephalin, D-Penicillamine (2,5)-/metabolism
- Enkephalin, Leucine/metabolism
- Enkephalin, Methionine/metabolism
- Humans
- Molecular Sequence Data
- Naloxone/metabolism
- Phylogeny
- Receptors, Opioid, delta/genetics
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, mu/genetics
- Receptors, Opioid, mu/metabolism
- Salamandridae/physiology
- Sequence Alignment
- beta-Endorphin/metabolism
Collapse
Affiliation(s)
- C Samuel Bradford
- Department of Zoology, Oregon State University, Corvallis, OR 97331, USA.
| | | | | | | | | |
Collapse
|
15
|
Clark MJ, Furman CA, Gilson TD, Traynor JR. Comparison of the relative efficacy and potency of mu-opioid agonists to activate Galpha(i/o) proteins containing a pertussis toxin-insensitive mutation. J Pharmacol Exp Ther 2006; 317:858-64. [PMID: 16436499 DOI: 10.1124/jpet.105.096818] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pertussis toxin (PTX)-insensitive mutants of Galpha(i/o) proteins expressed in C6mu cells were used to examine the hypothesis that there are agonist-specific conformational states of the mu-opioid receptor with coupling preferences to different Galpha(i/o) subtypes, as measured by the degree of stimulation of [(35)S]guanosine 5'-O-(3-thio)triphosphate (GTPgammaS) binding. Binding of [(35)S]GTPgammaS to endogenous Galpha(i/o) proteins stimulated by the full mu-opioid agonist [d-Ala(2),MePhe(4),Gly(5)-ol]enkephalin (DAMGO) was completely blocked by overnight treatment with 100 ng/ml PTX. Treatment for 4 h with lower concentrations led to a PTX-dependent reduction in the maximal effect of DAMGO but no alteration in the potency of DAMGO or morphine nor in the relative maximal effect (relative efficacy) of the partial agonists morphine and buprenorphine compared with the full agonist DAMGO. Using PTX-insensitive Galpha mutants in which the PTX-sensitive cysteine was replaced with isoleucine, the potency for a series of mu-opioid agonists was highest in cells expressing Galpha(i3) and Galpha(o) and lowest with Galpha(i1) and Galpha(i2), with no significant change in the order of potency, namely, etorphine >> endomorphin-1 = DAMGO = endomorphin-2 = fentanyl = morphine >> meperidine. The order of agonist relative efficacy, etorphine = DAMGO = endomorphin-1 = endomorphin-2 = fentanyl > or = morphine > or = meperidine > buprenorphine > or = nalbuphine, was also the same across all of the PTX-insensitive Galpha(i/o) subtypes. Highest relative efficacy to stimulate [(35)S]GTPgammaS binding was seen with Galpha(i3). Consequently, reported observations of agonist-directed trafficking at mu-opioid receptors most likely involve non-PTX-sensitive Galpha protein mechanisms.
Collapse
Affiliation(s)
- Mary J Clark
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109-0632, USA
| | | | | | | |
Collapse
|
16
|
Guan JS, Xu ZZ, Gao H, He SQ, Ma GQ, Sun T, Wang LH, Zhang ZN, Lena I, Kitchen I, Elde R, Zimmer A, He C, Pei G, Bao L, Zhang X. Interaction with vesicle luminal protachykinin regulates surface expression of delta-opioid receptors and opioid analgesia. Cell 2005; 122:619-31. [PMID: 16122428 DOI: 10.1016/j.cell.2005.06.010] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2004] [Revised: 04/11/2005] [Accepted: 06/07/2005] [Indexed: 11/24/2022]
Abstract
Opioid and tachykinin systems are involved in modulation of pain transmission in the spinal cord. Regulation of surface opioid receptors on nociceptive afferents is critical for opioid analgesia. Plasma-membrane insertion of delta-opioid receptors (DORs) is induced by stimulus-triggered exocytosis of DOR-containing large dense-core vesicles (LDCVs), but how DORs become sorted into the regulated secretory pathway is unknown. Here we report that direct interaction between protachykinin and DOR is responsible for sorting of DORs into LDCVs, allowing stimulus-induced surface insertion of DORs and DOR-mediated spinal analgesia. This interaction is mediated by the substance P domain of protachykinin and the third luminal domain of DOR. Furthermore, deletion of the preprotachykinin A gene reduced stimulus-induced surface insertion of DORs and abolished DOR-mediated spinal analgesia and morphine tolerance. Thus, protachykinin is essential for modulation of the sensitivity of nociceptive afferents to opioids, and the opioid and tachykinin systems are directly linked by protachykinin/DOR interaction.
Collapse
MESH Headings
- Afferent Pathways/drug effects
- Afferent Pathways/metabolism
- Afferent Pathways/ultrastructure
- Analgesics, Opioid/pharmacology
- Animals
- Cell Membrane/metabolism
- Cell Membrane/ultrastructure
- Cells, Cultured
- Ganglia, Spinal/drug effects
- Ganglia, Spinal/metabolism
- Ganglia, Spinal/ultrastructure
- Gene Deletion
- Male
- Mice
- Mice, Knockout
- Microscopy, Electron, Transmission
- Neurons, Afferent/drug effects
- Neurons, Afferent/metabolism
- Neurons, Afferent/ultrastructure
- Nociceptors/drug effects
- Nociceptors/metabolism
- Nociceptors/ultrastructure
- PC12 Cells
- Pain/drug therapy
- Pain/metabolism
- Pain/physiopathology
- Protein Precursors/chemistry
- Protein Precursors/genetics
- Protein Precursors/metabolism
- Protein Structure, Tertiary/physiology
- Rats
- Receptor Aggregation/physiology
- Receptors, Cell Surface/metabolism
- Receptors, Opioid, delta/metabolism
- Secretory Vesicles/metabolism
- Secretory Vesicles/ultrastructure
- Substance P/chemistry
- Substance P/metabolism
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
- Tachykinins/chemistry
- Tachykinins/genetics
- Tachykinins/metabolism
Collapse
Affiliation(s)
- Ji-Song Guan
- Institute of Neuroscience, Key Laboratory of Neurobiology, Chinese Academy of Sciences, Shanghai 200031, China
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Ott D, Neldner Y, Cèbe R, Dodevski I, Plückthun A. Engineering and functional immobilization of opioid receptors. Protein Eng Des Sel 2005; 18:153-60. [PMID: 15790572 DOI: 10.1093/protein/gzi012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Opioid receptors, like many G protein-coupled receptors (GPCRs), are notoriously unstable in detergents. We have now developed a more stable variant of the mu-opioid receptor (MOR) and also a method for the immobilization of solubilized, functional opioid receptors on a solid phase (magnetic beads). Starting with the intrinsically more stable kappa-opioid receptor (KOR), we optimized the conditions (i.e. detergents and stabilizing ligands) for receptor extraction from lipid bilayers of HEK293T cells to obtain maximal amounts of functional, immobilized receptor. After immobilization, the ligand binding profile remains the same as observed for the membrane-embedded receptor. For the immobilized wild-type mu-opioid receptor, however, no conditions were found under which ligand binding capacity was retained. To solve this problem, we engineered the receptor chimera KKM where the N-terminus and the first transmembrane helix (TM1) of wild-type MOR is exchanged for the homologous receptor parts of the wild-type KOR. This hybrid receptor behaves exactly as the wild-type MOR in functional assays. Interestingly, the modified MOR is expressed at six times higher levels than wild-type MOR and is similarly stable as wild-type KOR after immobilization. Hence the immobilized MOR, represented by the chimera KKM, is now also amenable for biophysical characterization. These results are encouraging for future stability engineering of GPCRs.
Collapse
Affiliation(s)
- David Ott
- Biochemisches Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | | | | | | | | |
Collapse
|
18
|
Marie N, Landemore G, Debout C, Jauzac P, Allouche S. Pharmacological characterization of AR-M1000390 at human delta opioid receptors. Life Sci 2003; 73:1691-704. [PMID: 12875901 DOI: 10.1016/s0024-3205(03)00489-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We investigated the pharmacological properties of a newly synthesised delta agonist AR-M1000390, derived from SNC-80 ((+)-4-[(alpha R)-alpha-((2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl]-N,N-diethyl-benzamide), in the neuroblastoma cell line SK-N-BE expressing only human delta-opioid receptors. Binding and functional experiments showed a weak affinity (K(i) = 106 +/- 34 nM) correlated with a weak potency (EC(50) = 111 +/- 31 nM) to inhibit the forskolin-stimulated cAMP accumulation. Sustained activation of opioid receptors in the presence of the maximal inhibitory concentration of AR-M1000390 produced a rapid and strong desensitization. In order to examine the contribution of internalization and down-regulation in the desensitization processes, binding and functional experiments were conducted in the presence or in the absence of hypertonic sucrose solution to block clathrin-dependent opioid receptor endocytosis. We observed both the inability of AR-M1000390 to down-regulate opioid receptors and the absence of any effect of sucrose on desensitization. The lack of delta-opioid receptor internalization by AR-M1000390 was further corroborated by confocal microscopy using antibodies directed either against the endogenous delta-opioid receptors or the FLAG-tagged delta-opioid receptors stably expressed in the SK-N-BE cells. These data suggest that uncoupling rather than internalization is responsible for delta-opioid receptors desensitization by AR-M1000390.
Collapse
Affiliation(s)
- Nicolas Marie
- Laboratoire de Pharmacologie moléculaire de la tolérance aux opiacés, Université de Caen, Caen, France
| | | | | | | | | |
Collapse
|
19
|
Abstract
The sequencing of the human genome is only the first step. The next step is to determine the function of these genes and in particular, how alterations in specific genes lead to major human disorders. Many laboratories are now focusing on identifying and characterizing single nucleotide polymorphisms (SNPs), to determine which correlate in frequency with certain population groups who may be particularly susceptible to certain diseases. The mu opioid receptor (MOR), which mediates the clinically important analgesic effects of drugs like morphine as well as the euphoria sought by heroin abusers, exhibits several dozen polymorphisms. Several of these are associated with altered receptor function and individuals at risk for drug abuse.
Collapse
Affiliation(s)
- Nancy M Lee
- California Pacific Medical Center Research Institute, 2330 Clay Street, Stern Bldg., San Francisco, CA 94115, USA.
| | | |
Collapse
|
20
|
McFadyen IJ, Metzger TG, Paterlini MG, Ferguson DM. Exploring the unique pharmacology of a novel opioid receptor, ZFOR1, using molecular modeling and the 'message-address' concept. Protein Eng Des Sel 2001; 14:953-60. [PMID: 11809925 DOI: 10.1093/protein/14.12.953] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Previous studies have probed the structural basis of ligand selectivity in the mu, delta and kappa opioid receptors through the application of molecular modeling techniques in concert with the 'message-address' concept. Here, this approach was used in an attempt to rationalize the unique pharmacological profile of a recently cloned novel opioid receptor, ZFOR1 (ZebraFish Opioid Receptor 1). Specifically, a model of the transmembrane domains of ZFOR1 was constructed and used to explore the binding modes of various prototypical opioid ligands. The results show that the 'message' portion of the binding pocket of ZFOR1 is highly conserved; hence, the binding modes of non-selective opioid ligands are well preserved. In contrast, a small number of variant residues at the extracellular end of the binding pocket, particularly Lys288 (VI:26) and Trp304 (VII:03), are shown to create adverse steric interactions with all delta and kappa selective ligands examined, thereby disrupting their binding modes. These results are consistent with, and serve as an explanation for, the observed pharmacology of this receptor, lending support to both the validity of the 'message-address' concept itself and to the use of molecular modeling approaches in its application.
Collapse
Affiliation(s)
- I J McFadyen
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55414, USA
| | | | | | | |
Collapse
|
21
|
Pil J, Tytgat J. The role of the hydrophilic Asn230 residue of the mu-opioid receptor in the potency of various opioid agonists. Br J Pharmacol 2001; 134:496-506. [PMID: 11588103 PMCID: PMC1572970 DOI: 10.1038/sj.bjp.0704263] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. To investigate the effect of the hydrophilic Asn amino acid at position 230 of the human mu-opioid receptor (hMOR230) on the potency of various agonists, we mutated this residue to Thr and Leu (hMORN230T and hMORN230L respectively). 2. Taking advantage of the functional coupling of the opioid receptor with the heteromultimeric G-protein-coupled inwardly rectifying K(+) (GIRK1/GIRK2) channel, either the wild type hMOR or one of the mutated receptors (hMORN230L or hMORN230T) were functionally coexpressed with GIRK1/GIRK2 channels and a regulator of G-protein signalling (RGS4) in Xenopus laevis oocytes. 3. The two-microelectrode voltage clamp technique was used to measure the opioid receptor-activated GIRK1/GIRK2 channel responses. The potency of [D-Ala(2),N-MePhe(4),Gly(5)-ol]-enkephalin (DAMGO), remained unaffected as measured via hMORN230T and hMORN230L, while the potency of fentanyl and morphine significantly increased via these mutated receptors. 4. Our results are indicative for the existence of hydrophobic interactions between a methyl-group of the side chain of Thr or Leu on the one hand and the piperidine-ring of fentanyl and the hexene-ring of morphine on the other. The mutations also had no influence on the potency of morphine-6-glucuronide (M6G) and morphine-3-glucuronide (M3G). 5. We conclude that the hydrophilic side chain of Asn in position 230 is not involved in the formation of a H-bond with the aliphatic alcohol of morphine and that an enhancement of the potency of morphine and fentanyl can be explained by mutating this residue towards more hydrophobic amino acids.
Collapse
MESH Headings
- Analgesics, Opioid/pharmacology
- Animals
- Asparagine/agonists
- Asparagine/biosynthesis
- Asparagine/genetics
- Asparagine/physiology
- Binding Sites/physiology
- Dose-Response Relationship, Drug
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Female
- G Protein-Coupled Inwardly-Rectifying Potassium Channels
- Humans
- Membrane Potentials/drug effects
- Membrane Potentials/physiology
- Mice
- Mutation/physiology
- Potassium Channels/biosynthesis
- Potassium Channels, Inwardly Rectifying
- RGS Proteins/biosynthesis
- Rats
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/biosynthesis
- Receptors, Opioid, mu/physiology
- Xenopus
Collapse
Affiliation(s)
- Joost Pil
- Laboratory of Toxicology, Faculty of Pharmaceutical Sciences, University of Leuven, Van Evenstraat 4, B-3000 Leuven, Belgium
| | - Jan Tytgat
- Laboratory of Toxicology, Faculty of Pharmaceutical Sciences, University of Leuven, Van Evenstraat 4, B-3000 Leuven, Belgium
- Author for correspondence:
| |
Collapse
|
22
|
Abstract
Significant advances have been made in understanding the structure, function, and regulation of opioid receptors and endogenous opioid peptides since their discovery approximately 25 years ago. This review summarizes recent studies aimed at identifying key amino acids that confer ligand selectivity to the opioid receptors and that are critical constituents of the ligand binding sites. A molecular model of the delta receptor based on the crystal structure of rhodopsin is presented. Agonist-induced down regulation of opioid receptors is discussed, highlighting recent evidence for the involvement of the ubiquitin/proteasome system in this process.
Collapse
Affiliation(s)
- K Chaturvedi
- Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, NJ 07103, USA
| | | | | | | |
Collapse
|
23
|
El Kouhen R, Burd AL, Erickson-Herbrandson LJ, Chang CY, Law PY, Loh HH. Phosphorylation of Ser363, Thr370, and Ser375 residues within the carboxyl tail differentially regulates mu-opioid receptor internalization. J Biol Chem 2001; 276:12774-80. [PMID: 11278523 DOI: 10.1074/jbc.m009571200] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Prolonged activation of opioid receptors leads to their phosphorylation, desensitization, internalization, and down-regulation. To elucidate the relationship between mu-opioid receptor (MOR) phosphorylation and the regulation of receptor activity, a series of receptor mutants was constructed in which the 12 Ser/Thr residues of the COOH-terminal portion of the receptor were substituted to Ala, either individually or in combination. All these mutant constructs were stably expressed in human embryonic kidney 293 cells and exhibited similar expression levels and ligand binding properties. Among those 12 Ser/Thr residues, Ser(363), Thr(370), and Ser(375) have been identified as phosphorylation sites. In the absence of the agonist, a basal phosphorylation of Ser(363) and Thr(370) was observed, whereas [d-Ala(2),Me-Phe(4),Gly(5)-ol]enkephalin (DAMGO)-induced receptor phosphorylation occurs at Thr(370) and Ser(375) residues. Furthermore, the role of these phosphorylation sites in regulating the internalization of MOR was investigated. The mutation of Ser(375) to Ala reduced the rate and extent of receptor internalization, whereas mutation of Ser(363) and Thr(370) to Ala accelerated MOR internalization kinetics. The present data show that the basal phosphorylation of MOR could play a role in modulating agonist-induced receptor internalization kinetics. Furthermore, even though mu-receptors and delta-opioid receptors have the same motif encompassing agonist-induced phosphorylation sites, the different agonist-induced internalization properties controlled by these sites suggest differential cellular regulation of these two receptor subtypes.
Collapse
Affiliation(s)
- R El Kouhen
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA.
| | | | | | | | | | | |
Collapse
|
24
|
Befort K, Filliol D, Decaillot FM, Gaveriaux-Ruff C, Hoehe MR, Kieffer BL. A single nucleotide polymorphic mutation in the human mu-opioid receptor severely impairs receptor signaling. J Biol Chem 2001; 276:3130-7. [PMID: 11067846 DOI: 10.1074/jbc.m006352200] [Citation(s) in RCA: 185] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Large scale sequencing of the human mu-opioid receptor (hMOR) gene has revealed polymorphic mutations that occur within the coding region. We have investigated whether the mutations N40D in the extracellular N-terminal region, N152D in the third transmembrane domain, and R265H and S268P in the third intracellular loop alter functional properties of the receptor expressed in mammalian cells. The N152D receptor was produced at low densities. Binding affinities of structurally diverse opioids (morphine, diprenorphine, DAMGO and CTOP) and the main endogenous opioid peptides (beta-endorphin, [Met]enkephalin, and dynorphin A) were not markedly changed in mutant receptors (<3-fold). Receptor signaling was strongly impaired in the S268P mutant, with a reduction of efficacy and potency of several agonists (DAMGO, beta-endorphin, and morphine) in two distinct functional assays. Signaling at N40D and R265H mutants was highly similar to wild type, and none of the mutations induced detectable constitutive activity. DAMGO-induced down-regulation of receptor-binding sites, following 20 h of treatment, was identical in wild-type and mutant receptors. Our data show that natural sequence variations in hMOR gene have little influence on ligand binding or receptor down-regulation but could otherwise modify receptor density and signaling. Importantly, the S268P mutation represents a loss-of-function mutation for the human mu-opioid receptor, which may have an incidence on opioid-regulated behaviors or drug addiction in vivo.
Collapse
MESH Headings
- Analgesics, Opioid/pharmacology
- Animals
- Asparagine/genetics
- Aspartic Acid/genetics
- COS Cells
- Cells, Cultured
- Cyclic AMP/metabolism
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
- Humans
- Mutagenesis, Site-Directed
- Narcotics/pharmacology
- Polymorphism, Single Nucleotide
- Proline/genetics
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/genetics
- Receptors, Opioid, mu/metabolism
- Serine/genetics
- Signal Transduction/physiology
- Sulfur Radioisotopes
Collapse
Affiliation(s)
- K Befort
- Laboratoire des Récepteurs et Protéines Membranaires, UPR CNRS 9050, ESBS, Parc d'Innovation, 67400 Illkirch, France
| | | | | | | | | | | |
Collapse
|
25
|
Macé G, Jaume M, Druet E, Blanpied C, Nguyen C, Druet P, Dietrich G. Identification of mu-opioid receptor epitopes recognized by agonistic IgG. Biochem Biophys Res Commun 2001; 280:1142-7. [PMID: 11162646 DOI: 10.1006/bbrc.2001.4258] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have previously reported the presence of IgG antibodies with a morphine-like activity in the serum of healthy individuals. The agonistic activity of IgG was dependent on their binding to the first and the third extracellular loops of the human mu opioid receptor. In this study we show that IgG antibodies obtained by immunizing rats with peptides corresponding to these two loops exhibited a similar morphine-like activity. Residues corresponding to Y(130), M(132), G(133), T(134) within the first and F(315) within the third extracellular segment were required for antibody binding and conferred to IgG a high mu-opioid selectivity.
Collapse
Affiliation(s)
- G Macé
- Institut National de la Santé et de la Recherche Médicale U28, Université Paul Sabatier, Place du Dr Baylac, Toulouse, 31059, France
| | | | | | | | | | | | | |
Collapse
|
26
|
Sánchez-Blázquez P, Gómez-Serranillos P, Garzón J. Agonists determine the pattern of G-protein activation in mu-opioid receptor-mediated supraspinal analgesia. Brain Res Bull 2001; 54:229-35. [PMID: 11275413 DOI: 10.1016/s0361-9230(00)00448-2] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The opioids heroin, methadone, buprenorphine, and morphine produce supraspinal antinociception in CD-1 mice that is antagonized by Cys(2), Tyr(3), Orn(5), Pen(7)-amide but not by naltrindole or nor-binaltorphimine. The patterns of GTP-binding regulatory proteins (G-proteins) activation exhibited by these agonists at mu-opioid receptors were characterized. The expression of alpha-subunits of Gi-protein classes, Gi1, Gi2, Gi3, Go1, Go2 and Gz, and those of the Gq-protein family, Gq and G11, was reduced by administration of antisense oligodeoxynucleotides (ODNs) complementary to sequences in their respective mRNAs. The ODN treatments demonstrated differences in the analgesic profiles of these opioids. Though the knock-down of G(i2)alpha or G(z)alpha subunits diminished the analgesic effects of the four opioids, impairment of G(i3)alpha did not modify the potency of morphine. In mice with reduced G(i1)alpha, G(o1)alpha or G(11)alpha levels, antinociception induced by heroin and methadone was diminished, but buprenorphine and morphine showed no change in their effects. Also, antinociception induced by heroin and buprenorphine, but neither morphine nor methadone, required intact G(o2)alpha or G(q)alpha levels. Thus, morphine, heroin, methadone, and buprenorphine showed different patterns of G-protein activation in evoking mu-opioid receptor-mediated supraspinal antinociception. Therefore, after binding identical receptors, each agonist determines the classes of GTP-binding regulatory transducer proteins to be activated.
Collapse
|
27
|
Tokita K, Hocart SJ, Katsuno T, Mantey SA, Coy DH, Jensen RT. Tyrosine 220 in the 5th transmembrane domain of the neuromedin B receptor is critical for the high selectivity of the peptoid antagonist PD168368. J Biol Chem 2001; 276:495-504. [PMID: 11013243 DOI: 10.1074/jbc.m006059200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Peptoid antagonists are increasingly being described for G protein-coupled receptors; however, little is known about the molecular basis of their binding. Recently, the peptoid PD168368 was found to be a potent selective neuromedin B receptor (NMBR) antagonist. To investigate the molecular basis for its selectivity for the NMBR over the closely related receptor for gastrin-releasing peptide (GRPR), we used a chimeric receptor approach and a site-directed mutagenesis approach. Mutated receptors were transiently expressed in Balb 3T3. The extracellular domains of the NMBR were not important for the selectivity of PD168368. However, substitution of the 5th upper transmembrane domain (uTM5) of the NMBR by the comparable GRPR domains decreased the affinity 16-fold. When the reverse study was performed by substituting the uTM5 of NMBR into the GRPR, a 9-fold increase in affinity occurred. Each of the 4 amino acids that differed between NMBR and GRPR in the uTM5 region were exchanged, but only the substitution of Phe(220) for Tyr in the NMBR caused a decrease in affinity. When the reverse study was performed to attempt to demonstrate a gain of affinity in the GRPR, the substitution of Tyr(219) for Phe caused an increase in affinity. These results suggest that the hydroxyl group of Tyr(220) in uTM5 of NMBR plays a critical role for high selectivity of PD168368 for NMBR over GRPR. Receptor and ligand modeling suggests that the hydroxyl of the Tyr(220) interacts with nitrophenyl group of PD168368 likely primarily by hydrogen bonding. This result shows the selectivity of the peptoid PD168368, similar to that reported for numerous non-peptide analogues with other G protein-coupled receptors, is primarily dependent on interaction with transmembrane amino acids.
Collapse
Affiliation(s)
- K Tokita
- Digestive Diseases Branch, NIDDK, National Institutes of Health, Bethesda, Maryland 20892-1804, USA
| | | | | | | | | | | |
Collapse
|
28
|
Barrallo A, González-Sarmiento R, Alvar F, Rodríguez RE. ZFOR2, a new opioid receptor-like gene from the teleost zebrafish (Danio rerio). BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2000; 84:1-6. [PMID: 11113526 DOI: 10.1016/s0169-328x(00)00152-2] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A new opioid receptor-like (ZFOR2) has been cloned and characterized in an anamniote vertebrate, the teleost zebrafish (Danio rerio). ZFOR2 encodes a 384-amino-acid protein with seven potential transmembrane domains, and its predicted amino acid sequence presents an overall 74% degree of identity to mammalian mu opioid receptors. Its inclusion in a dendrogram generated from the alignment of the opioid receptor's protein sequences, confirms its classification as a mu opioid receptor. Divergences in sequence are greater in the regions corresponding to extracellular loops, suggesting possible differences in ligand selectivity with respect to the classical mu opioid receptors. The genomic structure of ZFOR2 is also highly conserved throughout the phylogenetic scale, supporting the origin of opioid receptors early in evolution. Nevertheless, ZFOR2 lacks the fourth exon found in human and rodent mu opioid receptors, that is known to be involved in desensibilization and internalization processes.
Collapse
Affiliation(s)
- A Barrallo
- Department of Biochemistry and Molecular Biology, Department of Medicine, Faculty of Medicine, University of Salamanca, Campus Unamuno, Salamanca 37007, Spain
| | | | | | | |
Collapse
|
29
|
Chaturvedi K, Jiang X, Christoffers KH, Chinen N, Bandari P, Raveglia LF, Ronzoni S, Dondio G, Howells RD. Pharmacological profiles of selective non-peptidic delta opioid receptor ligands. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2000; 80:166-76. [PMID: 11038249 DOI: 10.1016/s0169-328x(00)00134-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Several non-peptidic opioids have been synthesized recently as part of a program to develop selective delta receptor agonists. In this study, the affinities of a set of compounds for cloned delta and mu opioid receptors expressed in HEK 293 cell lines were determined by competition analysis of [3H]bremazocine binding to membrane preparations. All compounds studied exhibited high affinity and selectivity, with apparent dissociation constants in the range of 0.6-1.7 nM for the delta opioid receptor and 240-1165 nM for the mu opioid receptor. We next sought to determine which domain of the delta receptor was critical for mediating the highly selective binding by analysis of ligand affinities for mu/delta receptor chimeras. Receptor binding profiles suggested that a critical site of receptor/ligand interaction was located between transmembrane domain 5 (TM5) and TM7 of the delta receptor. Substitution of tryptophan 284, located at the extracellular surface of TM6, with lysine, which is found at the equivalent position in the mu opioid receptor, led to a spectrum of effects on affinities, depending on the ligand tested. Affinities of SB 219825 and SB 222941 were particularly sensitive to the substitution, displaying a 50-fold and 70-fold decrease in affinity, respectively. Activities of the delta receptor-selective agonists were tested in two functional assays. Brief exposure of HEK 293 cells expressing delta opioid receptors with selective ligands induced phosphorylation of MAP kinase, although the non-peptidic ligands were less efficacious than the enkephalin derivative DADL (Tyr-D-Ala-Gly-Phe-D-Leu). Similarly, chronic exposure of HEK 293 cells expressing delta opioid receptors with selective, non-peptidic ligands, with the exception of SB 206848, caused receptor down-regulation, however, the SB compounds were less efficacious than DADL.
Collapse
MESH Headings
- Amino Acid Sequence
- Analgesics/metabolism
- Analgesics/pharmacology
- Analgesics, Opioid/metabolism
- Analgesics, Opioid/pharmacology
- Benzomorphans/metabolism
- Benzomorphans/pharmacology
- Binding, Competitive
- Cells, Cultured
- Cloning, Molecular
- Down-Regulation/drug effects
- Down-Regulation/physiology
- Enkephalin, Leucine-2-Alanine/pharmacology
- GTP-Binding Proteins/metabolism
- Heterocyclic Compounds, 4 or More Rings/chemistry
- Heterocyclic Compounds, 4 or More Rings/pharmacology
- Humans
- Indoles/chemistry
- Indoles/pharmacology
- Isoquinolines/chemistry
- Isoquinolines/pharmacology
- Kidney/cytology
- Ligands
- Mitogen-Activated Protein Kinases/metabolism
- Molecular Sequence Data
- Morphine/metabolism
- Morphine/pharmacology
- Mutagenesis, Site-Directed
- Naloxone/pharmacology
- Narcotic Antagonists/pharmacology
- Quinolines/chemistry
- Quinolines/metabolism
- Quinolines/pharmacology
- Radioligand Assay
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, delta/antagonists & inhibitors
- Receptors, Opioid, delta/genetics
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, Opioid, mu/genetics
- Tritium
Collapse
Affiliation(s)
- K Chaturvedi
- Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, 185 South Orange Avenue, 07103, Newark, NJ, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Ide S, Sakano K, Seki T, Awamura S, Minami M, Satoh M. Endomorphin-1 discriminates the mu-opioid receptor from the delta- and kappa-opioid receptors by recognizing the difference in multiple regions. JAPANESE JOURNAL OF PHARMACOLOGY 2000; 83:306-11. [PMID: 11001176 DOI: 10.1254/jjp.83.306] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Endomorphin-1 is a novel endogenous peptide that is highly selective for the mu-opioid receptor over the delta- and kappa-opioid receptors. The structural basis of high selectivity of endomorphin-1 to the mu-opioid receptor was examined using chimeric receptors between mu- and delta-opioid receptors and those between mu- and kappa-opioid receptors. The chimeric receptors were constructed by using restriction enzyme sites intrinsically possessed by or introduced to the mu-, delta- and kappa-opioid receptor cDNAs. The junctions for the construction were located at the first intracellular loop (Bbs I site), third transmembrane domain (Afl III site) and fifth transmembrane domain (Bgl II site). The competitive binding assay using chimeric receptors revealed that the region from the Bbs I site to the Afl III site, including the first extracellular loop, contributes to the discrimination between mu- and delta-opioid receptors by endomorphin-1 more than any other regions. However, the region from the Afl III site to the Bgl II site and that from the Bgl II site to the carboxy terminal also somewhat contribute to the discrimination between mu- and delta-opioid receptors. For the discrimination between mu- and kappa-opioid receptors, two regions, that is, the region from the Bbs I site to the Afl III site and that from the Bgl II site to the carboxy terminal, were shown to be important. The present results show that endomorphin-1 discriminates the mu-opioid receptor from the other two types of opioid receptors by recognizing the differences in several amino acid residues widely distributed through the receptor structure. We previously reported that DAMGO, a synthetic highly mu-selective peptide, discriminates between mu- and delta-opioid receptors by recognizing the difference in only one amino acid residue and discriminates between mu- and kappa-opioid receptors by recognizing the difference in four residues localized in the restricted region. Although both endomorphin-1 and DAMGO are mu-opioid receptor selective peptides, molecular mechanisms for mu-selectivity are different between these peptides.
Collapse
MESH Headings
- Animals
- COS Cells
- Oligopeptides/metabolism
- Rats
- Receptors, Opioid, delta/chemistry
- Receptors, Opioid, delta/genetics
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, kappa/chemistry
- Receptors, Opioid, kappa/genetics
- Receptors, Opioid, kappa/metabolism
- Receptors, Opioid, mu/chemistry
- Receptors, Opioid, mu/genetics
- Receptors, Opioid, mu/metabolism
- Transfection
Collapse
Affiliation(s)
- S Ide
- Department of Molecular Pharmacology, Faculty of Pharmaceutical Sciences, Kyoto University, Japan
| | | | | | | | | | | |
Collapse
|
31
|
Abstract
The cloning of the opioid receptors allows the investigation of receptor domains involved in the peptidic and nonpeptidic ligand interaction and activation of the opioid receptors. Receptor chimera studies and mutational analysis of the primary sequences of the opioid receptors have provided insights into the structural domains required for the ligand recognition and receptor activation. In the current review, we examine the current reports on the possible involvement of extracellular domains and transmembrane domains in the high-affinity binding of peptidic and nonpeptidic ligands to the opioid receptor. The structural requirement for the receptors' selectivity toward different ligands is discussed. The receptor domains involved in the activation and subsequent cellular regulation of the receptors' activities as determined by mutational analysis will also be discussed. Finally, the validity of the conclusions based on single amino acid mutations is examined.
Collapse
Affiliation(s)
- P Y Law
- Department of Pharmacology, University of Minnesota, Minneapolis 55455-0217, USA.
| | | | | |
Collapse
|
32
|
Chaturvedi K, Shahrestanifar M, Howells RD. mu Opioid receptor: role for the amino terminus as a determinant of ligand binding affinity. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2000; 76:64-72. [PMID: 10719216 DOI: 10.1016/s0169-328x(99)00332-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The importance of the amino-terminal domain of the mu opioid receptor (MOR) as a component of the high affinity ligand-binding pocket was evaluated. A deletion mutant lacking 64 amino acids from the amino-terminus of MOR (DeltaN64) was constructed and expressed in HEK 293 cells. The affinities of bremazocine and cyclazocine were similar for the truncated and full-length MORs. Affinities of the mu receptor antagonist, naloxone, and the mu receptor agonist, morphine, were decreased 3.5-fold and 6-fold, respectively, for the truncated receptor relative to the wild-type MOR. Similarly, the affinities of the opioid peptide agonists, DAMGO (Tyr-D-Ala-Gly-MePhe-Gly-ol), beta-endorphin, and DADL (Tyr-D-Ala-Gly-Phe-D-Leu), for the DeltaN64 receptor were decreased from 3- to 8-fold as a result of the deletion. In contrast, the affinities of the alkaloid agonists, methadone and fentanyl, and the peptide agonists, endomorphin 1 and endomorphin 2, for the truncated receptor relative to MOR were reduced dramatically by 20- to 60-fold. MOR is glycosylated when expressed in HEK 293 cells; however, analysis of N-glycosidase F-treated membranes indicated that N-glycan chains within the amino-terminal domain of MOR do not contribute significantly to ligand affinities. These results indicate that amino acid residues within the amino-terminal domain of MOR play a crucial role in the composition of the binding pocket for a select group of agonists.
Collapse
Affiliation(s)
- K Chaturvedi
- Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, 185 South Orange Avenue, Newark, NJ 07103, USA
| | | | | |
Collapse
|
33
|
Abstract
G protein-coupled, seven-transmembrane segment receptors (GPCRs or 7TM receptors), with more than 1000 different members, comprise the largest superfamily of proteins in the body. Since the cloning of the first receptors more than a decade ago, extensive experimental work has uncovered multiple aspects of their function and challenged many traditional paradigms. However, it is only recently that we are beginning to gain insight into some of the most fundamental questions in the molecular function of this class of receptors. How can, for example, so many chemically diverse hormones, neurotransmitters, and other signaling molecules activate receptors believed to share a similar overall tertiary structure? What is the nature of the physical changes linking agonist binding to receptor activation and subsequent transduction of the signal to the associated G protein on the cytoplasmic side of the membrane and to other putative signaling pathways? The goal of the present review is to specifically address these questions as well as to depict the current awareness about GPCR structure-function relationships in general.
Collapse
Affiliation(s)
- U Gether
- Department of Medical Physiology, Panum Institute, University of Copenhagen, Denmark.
| |
Collapse
|
34
|
Endomorphin-1 Discriminates the μ-Opioid Receptor From the 5- and κ-Opioid Receptors by Recognizing the Difference in Multiple Regions. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s0021-5198(19)30565-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
35
|
Zhang P, Johnson PS, Zöllner C, Wang W, Wang Z, Montes AE, Seidleck BK, Blaschak CJ, Surratt CK. Mutation of human mu opioid receptor extracellular "disulfide cysteine" residues alters ligand binding but does not prevent receptor targeting to the cell plasma membrane. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1999; 72:195-204. [PMID: 10529478 DOI: 10.1016/s0169-328x(99)00241-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The mu opioid receptor, a primary site of action in the brain for opioid neuropeptides and opiate drugs of abuse, is a member of the seven transmembrane, G protein-coupled receptor (GPCR) superfamily. Two cysteine residues, one in each of the first two of three extracellular loops (ECLs), are highly conserved among GPCRs, and there is direct or circumstantial evidence that the residues form a disulfide bond in many of these receptors. Such a bond would dramatically govern the topology of the ECLs, and possibly affect the position of the membrane-spanning domains. Recent findings from several laboratories indicate the importance of the ECLs for opioid ligand selectivity. These conserved cysteine residues in the mu opioid receptor were studied using site-directed mutagenesis. Little or no specific binding of radiolabled opiate alkaloid or opioid peptide agonists or antagonists was observed for receptors mutated at either "disulfide cysteine" residue. Each mutant mu opioid receptor was expressed in both transiently- and stably-transfected cells, in some cases at levels comparable to the wild type receptor. The two point mutants possessing serine-for-cysteine substitutions were also observed to successfully reach the cell plasma membrane, as evidenced by electron microscopy. Consistent with related work with other GPCRs, the mu opioid receptor apparently also employs the extracellular disulfide bond. This information now permits accurate molecular modeling of extracellular aspects of the receptor, including plausible scenarios of mu receptor docking of opioid ligands known to require specific extracellular loop features for high affinity binding.
Collapse
Affiliation(s)
- P Zhang
- Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD 21224, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Macé G, Blanpied C, Emorine LJ, Druet P, Dietrich G. Morphine-like activity of natural human IgG autoantibodies is because of binding to the first and third extracellular loops of the mu-opioid receptor. J Biol Chem 1999; 274:20079-82. [PMID: 10400617 DOI: 10.1074/jbc.274.29.20079] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have previously demonstrated that randomly selected healthy individuals express anti-human mu-opioid receptor antibodies which behave as agonist in vitro. In this study, we show that the activity of these antibodies was not affected by the deletion of the amino-terminal region of the receptor. Using agarose-bound peptide columns, we affinity-purified IgG specifically directed toward each extracellular loop. Whatever its specificity, each anti-human mu-opioid receptor (hMOR) extracellular loop peptide IgG preparation was unable, when examined individually, to reduce adenylate cyclase activity. Activation of the hMOR was, however, achieved by the simultaneous binding of IgG to the first and third extracellular loops of the receptor. Our results suggest that the simultaneous binding of IgG antibodies to these two loops mimics morphine-induced receptor activation by triggering a coordinated shift of the third and sixth transmembrane helices.
Collapse
Affiliation(s)
- G Macé
- INSERM U28 and Université Paul Sabatier, IFR 30, Hôpital Purpan, Place du Dr Baylac, 31059 Toulouse Cedex, France
| | | | | | | | | |
Collapse
|
37
|
Abstract
The deltorphins are a class of highly selective delta-opioid heptapeptides from the skin of the Amazonian frogs Phyllomedusa sauvagei and P. bicolor. The first of these fascinating peptides came to light in 1987 by cloning of the cDNA of from frog skins, while the other members of this family were identified either by cDNA or isolation of the peptides. The distinctive feature of deltorphins is the presence of a naturally occurring D-enantiomer at the second position in their common N-terminal sequence, Tyr-D-Xaa-Phe, comparable to dermorphin, which is the prototype of a group of mu-selective opioids from the same source. The D-amino acid and the anionic residues, either Glu or Asp, as well as their unique amino acid compositions are responsible for the remarkable biostability, high delta-receptor affinity, bioactivity and peptide conformation. This review summarizes a decade of research from many laboratories that defined which residues and substituents in the deltorphins interact with the delta-receptor and characterized pharmacological and physiological activities in vitro and in vivo. It begins with a historical description of the topic and presents general schema for the synthesis of peptide analogues of deltorphins A, B and C as a means to document the methods employed in producing a myriad of analogues. Structure activity studies of the peptides and their pharmacological activities in vitro are detailed in abundantly tabulated data. A brief compendium of the current level of knowledge of the delta-receptor assists the reader to appreciate the rationale for the design of these analogues. Discussion of the conformation of these peptides addresses how structure leads to further hypotheses regarding ligand receptor interaction. The review ends with a broad discussion of the potential applications of these peptides in clinical and therapeutic settings.
Collapse
Affiliation(s)
- L H Lazarus
- Peptide Neurochemistry, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | | | | | | |
Collapse
|
38
|
Gioannini TL, Onoprishvili I, Hiller JM, Simon EJ. Inactivation of the purified bovine mu opioid receptor by sulfhydryl reagents. Neurochem Res 1999; 24:37-42. [PMID: 9973235 DOI: 10.1023/a:1020923928936] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We have investigated the role of cysteine residues in a highly purified mu opioid receptor protein (muORP) by examining the effect of -SH reagents on the binding of opioid ligands. Treatment of muORP, which is devoid of additional proteins, eliminates complications that arise from reaction of -SH reagents with other components, such as G proteins. Reagents tested include N-ethylmaleimide, 5,5'-dithiobis(2-nitrobenzoic) acid, and two derivatives of methanethiosulfonate. Specific opioid binding was inactivated by micromolar concentrations of all -SH reagents tested. Agonist binding ([3H]DAMGO) was much more sensitive to inactivation than antagonist binding ([3H]bremazocine). Prebinding muORP with 100 nM naloxone protected antagonist and agonist binding from inactivation by -SH reagents. The results of these experiments strongly suggest that at least one, and possibly more, reactive cysteine residue(s) is present on the mu opioid receptor protein molecule, positioned near the ligand binding site and accessible to -SH reagents.
Collapse
Affiliation(s)
- T L Gioannini
- Natural Sciences Dept, Baruch College, City University of New York, NY 10010, USA
| | | | | | | |
Collapse
|
39
|
Pampusch MS, Osinski MA, Brown DR, Murtaugh MP. The porcine mu opioid receptor: molecular cloning and mRNA distribution in lymphoid tissues. J Neuroimmunol 1998; 90:192-8. [PMID: 9817447 DOI: 10.1016/s0165-5728(98)00142-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The porcine mu opioid receptor (pMOR), was cloned from cerebral cortex RNA using PCR methodologies. Porcine MOR is 96% identical with human MOR in amino acid sequence. An RT-PCR survey for pMOR mRNA indicated that pMOR is widely distributed in the gut, and is present in thymus and Peyer's patches but absent in other immune tissues and in isolated immune cells. Based on these findings, it appears that opioids do not exert an immunosuppressive effect through direct interaction with the mu-opioid receptor on immune cells. In certain tissues, however, opioids may modulate immune function indirectly through neuronal MOR.
Collapse
Affiliation(s)
- M S Pampusch
- Department of Veterinary PathoBiology, University of Minnesota, St. Paul 55108, USA.
| | | | | | | |
Collapse
|
40
|
Pogozheva ID, Lomize AL, Mosberg HI. Opioid receptor three-dimensional structures from distance geometry calculations with hydrogen bonding constraints. Biophys J 1998; 75:612-34. [PMID: 9675164 PMCID: PMC1299737 DOI: 10.1016/s0006-3495(98)77552-6] [Citation(s) in RCA: 150] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Three-dimensional structures of the transmembrane, seven alpha-helical domains and extracellular loops of delta, mu, and kappa opioid receptors, were calculated using the distance geometry algorithm, with hydrogen bonding constraints based on the previously developed general model of the transmembrane alpha-bundle for rhodopsin-like G-protein coupled receptors (Biophys. J. 1997. 70:1963). Each calculated opioid receptor structure has an extensive network of interhelical hydrogen bonds and a ligand-binding crevice that is partially covered by a beta-hairpin formed by the second extracellular loop. The binding cavities consist of an inner "conserved region" composed of 18 residues that are identical in delta, mu, and kappa opioid receptors, and a peripheral "variable region," composed of 19 residues that are different in delta, mu, and kappa subtypes and are responsible for the subtype specificity of various ligands. Sixteen delta-, mu-, or kappa-selective, conformationally constrained peptide and nonpeptide opioid agonists and antagonists and affinity labels were fit into the binding pockets of the opioid receptors. All ligands considered have a similar spatial arrangement in the receptors, with the tyramine moiety of alkaloids or Tyr1 of opioid peptides interacting with conserved residues in the bottom of the pocket and the tyramine N+ and OH groups forming ionic interactions or H-bonds with a conserved aspartate from helix III and a conserved histidine from helix VI, respectively. The central, conformationally constrained fragments of the opioids (the disulfide-bridged cycles of the peptides and various ring structures in the nonpeptide ligands) are oriented approximately perpendicular to the tyramine and directed toward the extracellular surface. The results obtained are qualitatively consistent with ligand affinities, cross-linking studies, and mutagenesis data.
Collapse
MESH Headings
- Algorithms
- Amino Acid Sequence
- Benzomorphans/metabolism
- Binding Sites
- Cell Membrane/physiology
- Cell Membrane/ultrastructure
- Enkephalin, D-Penicillamine (2,5)-
- Enkephalins/chemistry
- Enkephalins/metabolism
- GTP-Binding Proteins/metabolism
- Hydrogen Bonding
- Ligands
- Models, Chemical
- Models, Molecular
- Molecular Sequence Data
- Morphinans/metabolism
- Peptides, Cyclic/chemistry
- Peptides, Cyclic/metabolism
- Protein Structure, Secondary
- Receptors, Opioid, delta/chemistry
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, kappa/chemistry
- Receptors, Opioid, kappa/metabolism
- Receptors, Opioid, mu/chemistry
- Receptors, Opioid, mu/metabolism
- Rhodopsin/chemistry
- Sequence Alignment
- Sequence Homology, Amino Acid
- Substrate Specificity
Collapse
Affiliation(s)
- I D Pogozheva
- College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109 USA
| | | | | |
Collapse
|
41
|
Garzón J, Castro M, Sánchez-Blázquez P. Influence of Gz and Gi2 transducer proteins in the affinity of opioid agonists to mu receptors. Eur J Neurosci 1998; 10:2557-64. [PMID: 9767386 DOI: 10.1046/j.1460-9568.1998.00267.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The affinity displayed by different opioids to mu receptors (ORs) was determined in mouse brain membranes incubated with antibodies directed to Galpha subunits of the guanine nucleotide-binding proteins Gi2 and Gz. Assays were conducted with 10 pm 125I-Tyr27-beta-endorphin in the presence of 300 nm N, N-diallyl-Tyr-(alpha-aminoisobutyric acid)2-Phe-Leu-OH (ICI-174 864), which prevented the binding of the iodinated neuropeptide to delta-ORs. Gpp(NH)p or the preincubation of mouse brain membranes with IgGs to Gi2alpha or Gzalpha subunits, promoted reductions in the affinity exhibited by the labelled probe. The potencies of beta-endorphin, [D-Ala2,N-MePhe4,Gly-ol5]-enkephalin (DAMGO) and [D-Pen2,5]enkephalin (DPDPE) were reduced after impairing the coupling of mu-ORs to Gi2 or Gz proteins. Morphine showed a loss of affinity towards the mu-OR after preincubation of membranes with IgGs to Gzalpha subunits. However, it retained its potency after treatment with the anti-Gi2alpha IgGs. Conversely, [D-Ala2, D-Leu5]enkephalin (DADLE) and [D-Ser2, Leu5] enkephalin-Thr6 (DSLET) showed decreased affinity to mu-ORs after treatment with anti-Gi2alpha IgGs, with no noticeable change following the use of IgGs to Gzalpha subunits. The affinity exhibited by the opioid antagonists naloxone, naltrexone, naloxonazine and [Cys2,Tyr3,Orn5, Pen7 amide]somatostatin analogue (CTOP) remained unchanged after either treatment. Therefore, the affinity exhibited by opioid agonists of mu-ORs, but not antagonists, depends on the nature of the G-protein coupled to these receptors.
Collapse
MESH Headings
- Animals
- Antibodies/metabolism
- Binding, Competitive
- Brain/metabolism
- Cell Membrane/metabolism
- Dose-Response Relationship, Drug
- GTP-Binding Protein alpha Subunit, Gi2
- GTP-Binding Protein alpha Subunits
- GTP-Binding Protein alpha Subunits, Gi-Go
- GTP-Binding Proteins/immunology
- GTP-Binding Proteins/metabolism
- Heterotrimeric GTP-Binding Proteins
- Humans
- Iodine Radioisotopes
- Male
- Mice
- Monoiodotyrosine/metabolism
- Narcotic Antagonists/pharmacology
- Narcotics/agonists
- Narcotics/metabolism
- Narcotics/pharmacology
- Protein Binding/physiology
- Proto-Oncogene Proteins/immunology
- Proto-Oncogene Proteins/metabolism
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/metabolism
- beta-Endorphin/metabolism
Collapse
Affiliation(s)
- J Garzón
- Neurofarmacología, Instituto Cajal, Consejo Superior de Investigaciones Científicas, C/Dr Arce 37, 28002 Madrid, Spain.
| | | | | |
Collapse
|
42
|
Schiöth HB, Yook P, Muceniece R, Wikberg JE, Szardenings M. Chimeric melanocortin MC1 and MC3 receptors: identification of domains participating in binding of melanocyte-stimulating hormone peptides. Mol Pharmacol 1998; 54:154-61. [PMID: 9658201 DOI: 10.1124/mol.54.1.154] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The melanocortin receptors MC1 and MC3 are G protein-coupled receptors that have substantial structural similarities and bind melanocyte peptides but with different affinity profiles. We constructed a series of chimeric MC1/MC3 receptors to identify the epitopes that determine their selectivities for natural melanocyte peptides and synthetic analogues. The chimeric constructs were made by a polymerase chain reaction that used identical regions in or just outside transmembranes (TM) 1, 4, and 6 and divided the receptors into four segments. Saturation and competition studies on the expressed chimeric proteins indicate that TM1, TM2, TM3, and TM7 are involved in the subtype-specific binding of melanocyte peptides to these receptors. The results support the hypothesis that TM4 and TM5 may not contribute to the ligand-binding specificity of the MC receptors. This is the first report to describe the subtype-specific hormone-binding domains of the melanocortin receptor family.
Collapse
Affiliation(s)
- H B Schiöth
- Department of Pharmaceutical Pharmacology, Uppsala University, Uppsala, Sweden
| | | | | | | | | |
Collapse
|
43
|
Wu G, Lu ZH, Wei TJ, Howells RD, Christoffers K, Ledeen RW. The role of GM1 ganglioside in regulating excitatory opioid effects. Ann N Y Acad Sci 1998; 845:126-38. [PMID: 9668347 DOI: 10.1111/j.1749-6632.1998.tb09666.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Our studies with cultured cells have provided new insight into the particular role of GM1 in regulating excitatory opioid responses. GM1 is significantly elevated in chronic opioid-treated cells via Gs/adenylyl cyclase activation. Such GM1 elevation promotes coupling of opioid receptor with Gs, resulting in attenuation of inhibitory opioid effects and induction of a sustained excitatory response. Application of exogenous GM1, but not other gangliosides, induces excitatory opioid responses not only in neurons and neuroblastoma cells that bear intrinsic opioid receptors but also in nonneuronal cells that are transfected with delta-opioid receptor. The latter system provides evidence that allosteric binding of GM1 changes receptor conformation from a Gi-coupled to a Gs-coupled mode. This is supported by preliminary experiments with a mutated delta-opioid receptor.
Collapse
Affiliation(s)
- G Wu
- Department of Neurosciences, UMDNJ-New Jersey Medical School, Newark 07103, USA.
| | | | | | | | | | | |
Collapse
|
44
|
Seki T, Minami M, Nakagawa T, Ienaga Y, Morisada A, Satoh M. DAMGO recognizes four residues in the third extracellular loop to discriminate between mu- and kappa-opioid receptors. Eur J Pharmacol 1998; 350:301-10. [PMID: 9696421 DOI: 10.1016/s0014-2999(98)00240-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Previously, we reported that replacement of the region from the fifth transmembrane domain to the C-terminus of kappa-opioid receptor with the corresponding region of mu-opioid receptor gives high affinity for [D-Ala2, N-MePhe4, Gly-ol5]enkephalin (DAMGO), a mu-opioid receptor-selective ligand, to the resultant chimeric receptor, suggesting that the difference in the amino acid sequence within this region is critical for the discrimination between mu- and kappa-opioid receptors by DAMGO. In the present study, we constructed further six mu/kappa-chimeric receptors and revealed that at least two separate regions around the third extracellular loop are critical for the discrimination between mu- and kappa-opioid receptors by DAMGO. Furthermore, we constructed several mutant receptors by a site-directed mutagenesis technique and found that the difference between Glu297 of kappa-opioid receptor and Lys303 of mu-opioid receptor in one region, and the difference between Ser310, Tyr312 and Tyr313 of kappa-opioid receptor and Val316, Trp318 and His319 of mu-opioid receptor in the other region, are critical for the discrimination between these receptors by DAMGO. The mutant receptor, kappa (E297K + Y313H + Y312W + S310V), in which the Glu297, Ser310, Tyr312 and Tyr313 of kappa-opioid receptor were changed to Lys, Val, Trp and His, respectively, bound to DAMGO with high affinity (Kd = 8.7 +/- 1.2 nM) and efficiently mediated the inhibitory effect of DAMGO on intracellular cAMP accumulation. The present results showed that these four amino acid residues act as determinants for the discrimination between mu- and kappa-opioid receptors by DAMGO.
Collapse
MESH Headings
- Adenylyl Cyclases/metabolism
- Amino Acid Sequence
- Animals
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-
- Enkephalins/pharmacology
- Extracellular Space/drug effects
- Extracellular Space/genetics
- Extracellular Space/metabolism
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Mutation
- Protein Structure, Secondary
- Radioligand Assay
- Rats
- Receptors, Opioid, kappa/chemistry
- Receptors, Opioid, kappa/drug effects
- Receptors, Opioid, kappa/genetics
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/chemistry
- Receptors, Opioid, mu/genetics
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/metabolism
Collapse
Affiliation(s)
- T Seki
- Department of Molecular Pharmacology, Faculty of Pharmaceutical Sciences, Kyoto University, Japan
| | | | | | | | | | | |
Collapse
|
45
|
Szekeres PG, Koenig JA, Edwardson JM. The relationship between agonist intrinsic activity and the rate of endocytosis of muscarinic receptors in a human neuroblastoma cell line. Mol Pharmacol 1998; 53:759-65. [PMID: 9547368 DOI: 10.1124/mol.53.4.759] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The molecular mechanisms underlying the internalization of G protein-coupled receptors are still poorly understood. Normally agonists but not antagonists cause internalization (defined here as a reduction in the number of receptors at the cell surface), suggesting a functional relationship between agonist activity and internalization. In this study we investigated the effects of eight muscarinic ligands on the rate constants for endocytosis and recycling of m3 muscarinic acetylcholine receptors in human SH-SY5Y neuroblastoma cells. We found that there was a linear correlation between the intrinsic activity of the ligand and its ability to increase the rate constant for endocytosis, suggesting that the same active conformation of the receptor is responsible for stimulating both second messenger generation and receptor endocytosis. In contrast, the rate constant for recycling did not depend on which agonist had triggered receptor endocytosis, suggesting that recycling is a purely constitutive process. Because receptor internalization depends on the rate constants for both endocytosis and recycling, the relationship between internalization and intrinsic activity is nonlinear. In particular, mathematical modeling of receptor trafficking revealed that under certain conditions very small (3% or less) increases in the rate constant for endocytosis are sufficient to cause substantial receptor internalization. An important implication of this analysis is that extremely weak partial agonists (which may in practice be indistinguishable from antagonists) may produce significant receptor internalization.
Collapse
Affiliation(s)
- P G Szekeres
- Department of Pharmacology, University of Cambridge, United Kingdom
| | | | | |
Collapse
|
46
|
Meng F, Ueda Y, Hoversten MT, Taylor LP, Reinscheid RK, Monsma FJ, Watson SJ, Civelli O, Akil H. Creating a functional opioid alkaloid binding site in the orphanin FQ receptor through site-directed mutagenesis. Mol Pharmacol 1998; 53:772-7. [PMID: 9547370 DOI: 10.1124/mol.53.4.772] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although much has been learned about the mechanisms of ligand selectivity between different opioid receptor subtypes, little is known about the common opioid binding pocket shared by all opioid receptors. The recently discovered orphanin system offers a good opportunity to study the mechanisms involved in the binding of opioid versus nonopioid ligands. In the current study, we adopt a "gain of function" approach aimed at shifting the binding profile of the orphanin FQ receptor toward that of the opioid receptors. After two rounds of mutagenesis, several orphanin FQ receptor mutants can be labeled with the opiate alkaloid [3H]naltrindole and show greatly increased affinities toward the opiate antagonists naltrexone, nor-binaltrophine HCl, and (-)-bremazocine. These orphanin FQ receptor mutants also display stereospecificity similar to that of opioid receptors. Furthermore, the orphanin FQ receptor mutant that has the best affinities toward the opioid alkaloids shows, in the presence of GTP and high salt concentration, an affinity-shift profile similar to that of the delta receptor. Most strikingly, the same mutant exhibits naltrindole-sensitive etorphine-stimulated [35S]guanosine-5'-O-(3-thio)triphosphate binding, whereas the effect of etorphine on GTP binding cannot be inhibited by naltrindole in the wild-type receptor. Our results indicate that 1) several residues in the orphanin FQ receptor are critical to its selectivity against the opiate alkaloids, particularly antagonists; and 2) mutating these residues to those of the opioid receptor at the corresponding position preserves the agonist/antagonist nature of opiate alkaloids as they interact with the mutant receptor. It is reasonable to hypothesize that the corresponding residues in the opioid receptors may form a functional common binding pocket for opiate alkaloids. These findings may be helpful to medicinal chemists in designing ligands for the orphanin FQ receptor based on the structure of the opiate alkaloids.
Collapse
Affiliation(s)
- F Meng
- Mental Health Research Institute, University of Michigan, Ann Arbor 48109, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Bryant SD, Salvadori S, Cooper PS, Lazarus LH. New delta-opioid antagonists as pharmacological probes. Trends Pharmacol Sci 1998; 19:42-6. [PMID: 9550939 DOI: 10.1016/s0165-6147(97)01156-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- S D Bryant
- National Institute of Environmental Health Sciences, Research Triangle Park, NC 22709, USA
| | | | | | | |
Collapse
|
48
|
Mandell AJ, Selz KA, Shlesinger MF. Mode matches and their locations in the hydrophobic free energy sequences of peptide ligands and their receptor eigenfunctions. Proc Natl Acad Sci U S A 1997; 94:13576-81. [PMID: 9391068 PMCID: PMC28348 DOI: 10.1073/pnas.94.25.13576] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/1997] [Accepted: 09/11/1997] [Indexed: 02/05/2023] Open
Abstract
Patterns in sequences of amino acid hydrophobic free energies predict secondary structures in proteins. In protein folding, matches in hydrophobic free energy statistical wavelengths appear to contribute to selective aggregation of secondary structures in "hydrophobic zippers." In a similar setting, the use of Fourier analysis to characterize the dominant statistical wavelengths of peptide ligands' and receptor proteins' hydrophobic modes to predict such matches has been limited by the aliasing and end effects of short peptide lengths, as well as the broad-band, mode multiplicity of many of their frequency (power) spectra. In addition, the sequence locations of the matching modes are lost in this transformation. We make new use of three techniques to address these difficulties: (i) eigenfunction construction from the linear decomposition of the lagged covariance matrices of the ligands and receptors as hydrophobic free energy sequences; (ii) maximum entropy, complex poles power spectra, which select the dominant modes of the hydrophobic free energy sequences or their eigenfunctions; and (iii) discrete, best bases, trigonometric wavelet transformations, which confirm the dominant spectral frequencies of the eigenfunctions and locate them as (absolute valued) moduli in the peptide or receptor sequence. The leading eigenfunction of the covariance matrix of a transmembrane receptor sequence locates the same transmembrane segments seen in n-block-averaged hydropathy plots while leaving the remaining hydrophobic modes unsmoothed and available for further analyses as secondary eigenfunctions. In these receptor eigenfunctions, we find a set of statistical wavelength matches between peptide ligands and their G-protein and tyrosine kinase coupled receptors, ranging across examples from 13.10 amino acids in acid fibroblast growth factor to 2.18 residues in corticotropin releasing factor. We find that the wavelet-located receptor modes in the extracellular loops are compatible with studies of receptor chimeric exchanges and point mutations. A nonbinding corticotropin-releasing factor receptor mutant is shown to have lost the signatory mode common to the normal receptor and its ligand. Hydrophobic free energy eigenfunctions and their transformations offer new quantitative physical homologies in database searches for peptide-receptor matches.
Collapse
Affiliation(s)
- A J Mandell
- The Cielo Institute, 486 Sunset Drive, Asheville, NC 28804, USA
| | | | | |
Collapse
|
49
|
McClintock TS, Lerner MR. Functional analysis by imaging of melanophore pigment dispersion of chimeric receptors constructed by recombinant polymerase chain reaction. BRAIN RESEARCH. BRAIN RESEARCH PROTOCOLS 1997; 2:59-68. [PMID: 9438073 DOI: 10.1016/s1385-299x(97)00030-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Analysis of functional aspects of the molecular structure of proteins often requires a means to selectively alter structure and subsequently analyze function. We have adapted a method of overlap extension polymerase chain reaction (PCR) to generate multiple domain replacements in G-protein coupled receptors. The examples described herein are beta 2-adrenergic receptors whose G-protein coupling domains have been replaced by homologous domains of olfactory receptors, but the procedure has also been used to produce constructs with mutations, deletions, and fusions of two complete open reading frames. The chimeric olfactory-adrenergic receptors were assayed by functional expression in clonal lines of Xenopus melanophores. The ability of G-protein coupled second messenger pathways to cause translocation of pigment organelles within melanophores allows the use of video microscopy to assay the function of the chimeric receptors. Digital automation of microscope stage, camera, and image processing allows multiple parallel experiments to be performed. Melanophores allow responses mediated by the Gs, Gq and Gi pathways to be assayed with equal efficiency and the specificity of the coupling between chimera (or receptor) and G-protein subtypes can be rapidly determined.
Collapse
Affiliation(s)
- T S McClintock
- Department of Physiology, University of Kentucky, Lexington 40536-0084, USA.
| | | |
Collapse
|
50
|
Schiöth HB, Petersson S, Muceniece R, Szardenings M, Wikberg JE. Deletions of the N-terminal regions of the human melanocortin receptors. FEBS Lett 1997; 410:223-8. [PMID: 9237634 DOI: 10.1016/s0014-5793(97)00593-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The non-homologous N-terminal regions of four human melanocortin (MC) receptors were truncated in order to investigate their putative participation in ligand binding. Eleven constructs were made, where different numbers of residues from the N terminus were deleted. These constructs were used for transient expression experiments in COS cells and analysed by ligand binding. The results show that 27, 25, 28, and 20 amino acids could be deleted from the N terminus of the human MC1, MC3, MC4 and MC5 receptors, respectively, including all potential N-terminal glycosylation sites in the MC1 and the MC4 receptors, without affecting ligand binding or expression levels. The results indicate that the N-terminal regions of the human MC1, MC3, MC4 and MC5 receptors, do not play an important role for the ligand binding properties of these receptors.
Collapse
Affiliation(s)
- H B Schiöth
- Department of Pharmaceutical Pharmacology, Biomedical Center, Uppsala University, Sweden.
| | | | | | | | | |
Collapse
|